Piston for internal-combustion engines



F. O. BENOIST. PISTON FOR INTERNAL COMBUSTION ENGINES. APPLICATION FILED MAY 23. 192i.

JLAIQQYQMI Patented June 2a, 1922.

UNETEE TATS HFFHQ.

FRANK O. BENOIST, OF PHOENIX, ARIZONA, AS SIGNOB. T0 ARTHUR RICH THOMAS, OF PHOENIX, ARIZONA.

YISTON' FOR INTERNAL-COMBUSTION ENGINES.

Application filed May 23, 1921.

To all whom it may concern:

Be it known that I, FRANK O. BENOIST, a citizen of the United States, and a resident of Phoenix, in the county of Maricopa and State of Arizona, have inventeda certain new and useful Piston for- Internal-Combustion Engines, of which the following is a specification.

This invention relates to pistons for internal combustion engines.

In internal combustion engines, lubrication of the cylinders and pistons is almost invariably effected by providing a closed crank case adapted to contain oil which is in open communicationwith the engine cylinders, so that oil contained therein will be splashed over the parts of the cylinder and piston exposed in said crank case by the cranks of the engine and associated parts, when the engine is running.

As is well known to persons familiar with the construction and operation of internal combustion engines, the suction produced in the combustion space of the engine cylinder during the air and fuel admission stroke of the piston, causes lubricating oil to seep or leak between the cylinder walls and piston into the combustion space of the engine cylinder, where it will be ignited and burned upon ignition of the explosive mixture in the cylinder. This is objectionable for a number of reasons, among which are the following (a) loss of oil and the consequent necessity of the use of an excessive quantity of oil for properly lubricating the engine,

(7)) the burning oil produces a greatdeal of smoke, is dirty and malodorous and is of course discharged into the air; and (0) in burning, said lubricating oil produces a deposit of carbon on all parts of the engine exposed in the compression space of the cylinder, which materially impairs their eflicient operation. This is particularly the case with spark plugs, valves and valve seats.

The object of the invention is to provide a piston for internal combustion engines. so constructed that leakage from the crank case of the engine, past the piston into the compression space of the engine cylinder, with its attendant objectionable features, will be entirely prevented or so greatly reduced that the effects hereof will be unobjectionable. I

To effect the foregoing object, a piston of my invention comprises the various fea- Specification of Letters Patent.

Patented June 2t), 1922.

Serial No. 471,852.

tures, combinations of features and details of construction hereinafter described and claimed.

In the accompanying drawing in which my invention is fully illustrated,

Figure 1 is a side view of a piston embodying my invention and improvements, the piston rings being shown in section.

Figure 2 is an end view thereof from the left side of Figure 1.

Figure 3 is a sectional vlew on the line 3-3 of Fig. 1; and

Figure 4 is a fragmentary sectional view on the line 4:-4.

Referring now to the drawings, A desig nates, as a whole, the piston of an internal combustion engine. As regards its usual features and excepting as hereinafter particularly described, said piston may be of any usual or approved construction and will be readily understood by persons familiar with the construction of internal combustion engines from an examination of the drawings without a description thereof in detail. For

purposes of convenient reference, 1 desig nates the body portion of the piston, which that no appreciable leakage of lubricating oil occurs between the piston rings and walls of the cylinder, but that the leakage which produces the objectionable results above specified, occurs between the piston rings and the sides of the grooves in which they are confined-such leakage increasing as thepiston, cylinder, packing rings and packing ring grooves wear-and that leakage of oil into the compression space of the cylinder can be effectively prevented by forming holes or openings in the body portion 1 of the piston at the bottom of one or more of the piston ring grooves 4. As shown, said holes or openings are designated by the reference numeral 5 and are formed at bottom of the groove adjacent to the open end of the piston only.

I have discovered that to effectively prevent leakage of lubricating oil from the crank case to the compression space of the engine, it is necessary that said holes 5 shall be of considerable length circumferentially of the piston. while, to properly lubricate the piston of the cylinder, it is necessar that portions 6 of the bottom side on the groove in which said holes or openings are formed shall be left between said holes in order to permit a desired quantity of the lubricating oil to flow across same and thus to pass to the far side of the groove in which said holes or openings are'formed. Also, to effect a uniform distribution of the lubricating oil over the wearing surfaces of piston and c v1 inder, it is necessary that said portions 6 of the bottom sides of the groove between the holes or openings 5 shall be distributed uniformly around the'circumference of the piston.

In practice, I have found that very good results are obtained with holes 5 which are approximately twice as long, circumferentially of the piston, as the portions 6 of the bottom side of the groove between said holes, said holes and the sections of the bottom wall between the same bein respectively,

of substantially the same length and being arranged symmetrically around the piston.-

While the relative lengths of the holes or openings 5 and the intermediate portions 6 of the bot-tom side of said groove will vary with conditions, as for example with the size of the engine, the proper relation between said holes and portions of the bottom of said groove effectively prevent leakage and at the same time properly lubricate the wearing surfaces of the piston and cylinder can readily be ascertained by test and experiment.

As shown, the width of the holes 5 is equal to that of the groove in which they are formed.

The portions of the body portion 1 of the piston at opposite sides of the groove 4: in which the holes or openings '5 are formed are connected by ribs 7 formed on the inner wall of the body pcfition of the piston, the

portions 6 of the bottom of said groove,

being formedidirectly in said ribs,

Also. to properly balance the weight of. the piston at opposite sides of the bearings 2 for the connecting rod pin, a head 8, is

.preferably formed around the inside of the body portion 1 of the piston adjacent to the groove 4 in which the holes or openings 5 are formed, said head .being of such size that its weight will compensate for that of the metal removed by the formation of the holes or openings 5.

I claim.

- 1, A piston for an internal combustion engine provided with a groove for a piston ring and a piston ring confined in said groove, said piston being also provided with holes formed through the wall of the piston at the bottom of said piston ring groove, leaving portions of the bottom side of'said groove between adjacent holes, the length of said holes being proportioned 'to minimize leakage past said piston ring, and the length of the portions of the bottom of said groove between said holes being proportioned to permit enough leaking past said ring to properly lubricate the wearing surfaces of the piston and cylinder, substantially as described. i

2. A piston for an internal combustion engine as specified in claim 1, in which the holes at the bottom of the piston ring groove and the portions of the bottom side of said groove between said holes are arranged symmetrically, substantially as described.

3. A piston for an internal combustion engine as specified in claim 1, in which the holes at the bottom of the piston ring groove are longer than the portions of the bottom ranged symmetrically, substantially as described= A piston for an internal combustion engine as specified in claim 3, in which the holes at the bottom of the piston ring groove aresubstantially twice as long as the portions of the bottom of said groove between said holes, substantially as described.

6. A piston for an internal combustion engine as specified in claim 1,'in which the portions of the body portion of the piston at opposite sides of the piston ring grooves are connected by ribs formed on the inside wall of the piston, substantially as described.

7.. A piston for an internal combustion engine as specified in claim 6, in which the portions of the bottom of the piston ring groove between the holes formed therein, are formed in said ribs, substantially as described.

8. A piston for an internal combustion engine as specified in claim '1, in which a bead is formed on the inside of the body' portion of the piston adjacent to the piston ring groove. to compensate for the weight of the metal removed in the formation of the holes formed at the bottom. of said piston ring groove, substantially as described.

In witness that I claim the foregoing. as

my invention, I afilx my signature this 16th day of May, A. D. 1921. v FRANK O. BE'NOIST. 

